Rock crushers reduce the size of rocks in order to provide material for road beds, concrete, building foundations and the like. By definition, rock crushers need to be heavy duty to avoid breakage and bending during the crushing process. Rock crushers may be categorized as cone crushers, jaw crushers, and impact crusher, but this disclosure will focus on cone crushers. Cone crushers break up rocks and other hard material by squeezing or compressing product between convex and concave-shaped surfaces covered by hardened wear surfaces. Cone crushers are normally used as the second or third stage crusher, with a reduction ratio of from about 6 to 8 to 1.
Once such cone crusher is described in U.S. patent application Ser. No. 14/717,651, filed on May 20, 2015, which is incorporated herein by reference. This application describes a cone crusher that is conventional in much of its construction. It includes a conically-shaped head, which is part of an upper rock crusher assembly. The conical head both gyrates or oscillates and rotates relative to a stationary bowl that includes a hardened bowl liner. The spacing between the bowl liner and the cone at any given point opens and closes as the cone oscillates relative to and inside the bowl. Rocks are deposited in the spacing and the rocks slide down between these surfaces as the space opens, and the rocks are crushed as the space closes.
This crushing process develops tremendous pressures and tensions in the stationary frame surrounding the bowl line. To withstand these forces, the frame, sometimes called the base frame, other times called the bowl support, must be extremely heavy duty. This requires a substantial amount of steel, which is typically cast at great expense. It also is very heavy, creating transport difficulties, particularly if the cone crusher is part of a mobile crushing plant.
In attempts to reduce the amount of steel used in cone crusher frames, circumferential bands of steel are sometimes used in place of the entire frame being a thick wall of steel. While the use of circumferential bands may tend to reduce the required amount of steel in the rest of the frame, the bands are not as effective as they might be in spreading the crushing forces.